Abstract The majority of previous research on health and support among racial/ethnic minorities in the U.S. in general and among Latinos in particular, and among peoples of Latin American countries relies on the idea of familismo, the idea that family need is put before individual need. Although there is evidence supporting the benefits of strong family ties have for helping older adults in these settings delay or avoid institutional care, the proposed bi-national study is the first step toward assessing how Mexican and Mexican American families organize caregiving relationships for elderly family members who experience dementia. We propose to investigate trajectories of living arrangements and their relationship to dementia by employing the two largest epidemiologic surveys of older Mexican adults, the Hispanic Established Population of the Epidemiologic Study of the Elderly (H-EPESE) and the Mexican Health and Aging Study (MHAS). These studies contain a wide array of information regarding risk and protective factors for chronic diseases, dementia, dependency, socioeconomic characteristics, and living arrangements. One conceptual innovation of the proposed research is that the model for understanding the relationship between living arrangements and disability will serve as a prototype for future research on the dementia-related disablement processes for other racial/ethnic minority groups and bi-national comparisons with Mexico. By exploring the changing need for, and availability of, support, as dementia progresses, we can make better conclusions about the number of older Latinos at risk of being left without sound support and, consequently, highly dependent on public resources. We will estimate at which point in the disablement process interventions are most needed. The proposed project, by incorporating dementia, will also lead to the development of a more robust theoretical model for assessing disability and support need in older adults. Another innovative aspect of the proposed research is the use of quantitative, longitudinal data to examine the relationship between dementia and the need for assistance in two prospective cohort studies of older Mexicans in Mexico and Mexican-origin adults in the United States. We will examine patterns of stability and change in living arrangements among individuals with and without dementia; the extent to which migration to and from the U.S. affects morbidity; health and socioeconomic status; and other proximal factors to account for any differences. A key methodological innovation of this project is its move from static cross-sectional analyses and standard growth models to growth mixture modeling (GMM), which allows us to examine greater diversity in the lived experiences of older peoples with dementia in both nations. Altogether, this work will provide a deeper understanding of the role of dementia in the long-term family caregiving experience of the Mexican-origin population in both Mexico and the United States, and highlight the role of migration and socioeconomic factors in shaping social resources in a time of need.